Field of the Invention
This invention relates to novel comb graft polymers of p-methylstyrene (p-MS), particularly copolymers of p-MS with any of various comonomers, and the use of such polymers and copolymers as additives for functional fluids, e.g. lubricating oils.
Information Disclosure Statement Including Description of Related Art
Niwa et al., U.S. Pat. No. 4,912,170, disclose the lithiation of polymers of p-methylstyrene with an organic lithium compound, and the reaction of the lithiated polymer with a "delithiuming" compound causing functional substituting groups to form along the polymer chain which are then available for further reaction. There is no suggestion by these patentees of grafting any polymer chains at the lithium, i.e., anionic, sites.
Loveless, U.S. Pat. No. 3,925,511, discloses the metallation of activated hydrogen atoms along the chain of polymers such as polybutadiene or polystyrene, with an organolithium compound and a compound having the formula MOR" wherein M is sodium or potassium and R" is hydrogen or a hydrocarbon radical. The metallated polymer may then be reacted with an anionically polymerizable monomer to form a graft polymer. There is no disclosure by the patentee of graft polymers of a metallated backbone polymer of p-methylstyrene.
McCormick et al., U.S. Pat. No. 3,318,813, disclose polymers of alkylstyrenes, e.g., tert-butylstyrene, as additives for improving the viscosity index of lubricating oils. There is no suggestion in this patent of the use of any graft polymers.
Y. Minoura et al., "Anionic Graft Copolymerization of Diene Polymers with Vinyl Monomers," JOURNAL OF POLYMER SCIENCE: PART A-1, Vol. 7, 3-14 (1969), disclose the preparation of graft copolymers of lithiated polybutadiene or polyisoprene with styrene, methyl methacrylate or acrylonitrile. There is no disclosure in this reference of graft polymers of a lithiated p-methylstyrene polymer.